The present invention relates to a spacer device and a multilayer coil arrangement employing the spacer device between radial layers of the coil arrangement.
The structures of large scale (e.g., 50-500 meter radius) superconducting magnetic energy storage (SMES) coils typically include several radial coil winding layers. In general, during operation of the coil, the outermost coil layers exert an inward radial load (radially directed toward the center of the coil), while the innermost coil layers exert an outward load (radially directed away from the center of the coil). The result is a net outward radial pressure that is carried by the coil structure or transmitted to an external support system. Such SMES coils typically require that the radial electromagnetic pressure exerted between layers be reacted partially within the coil structure, e.g., by bending or flexing of the coil layers and by pressing adjacent coil layers against each other.
With coil designs that require the conductors to be exposed to a liquid helium bath (or with forced flow conductors), it would be desirable to separate the layers to allow helium to access the inner layer windings. However, electromagnetic forces present during the operation of SMES coils would normally collapse separated layers together. Therefore, it would be desirable to provide a system which would allow separated coil layers to react electromagnetic loads against each other and remain separated.